An interactive applet and associated web page that describe the Euler line. It shows a triangle whose vertices can be dragged.
As you drag them, the centroid, circumcenter and orthocenter mov...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that the definition of the center of a regular polygon.
The applet presents a regular polygon, where the user can drag any vertex to resize it, an...More: lessons, discussions, ratings, reviews,...

See the different centers of a triangle and how they are related to the medians, perpendicular bisectors, and altitudes of the triangle. Students can manipulate the triangle and try to answer the fol...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step instructions on how to find
the circumcircle of a triangle using only a compass and straightedge.
The method used involves...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that demonstrate how to construct the incircle of triangle using compass and straightedge.
It starts with a given triangle, and using animation tha...More: lessons, discussions, ratings, reviews,...

An interactive applet and associated web page that provide step-by-step instructions on how to construct the orthocenter of a triangle
using only a compass and straightedge.
The method used invo...More: lessons, discussions, ratings, reviews,...

Euclid's proposition shows how to inscribe a circle within a given triangle. The guide then examines the structure of the proposition. The To reset the applet, press "r" while your cursor is over th...More: lessons, discussions, ratings, reviews,...

Euclid's proposition shows how to circumscribe a circle about a given triangle. The guide then examines the structure of the proposition. The To reset the applet, press "r" while your cursor is over...More: lessons, discussions, ratings, reviews,...

The user is given 7 tasks. Each involves using estimation to achieve a geometric task. Two samples are: moving a ray so that it is an angle bisector, and moving a vertex of a quadrilateral so that it ...More: lessons, discussions, ratings, reviews,...

Intrigue students with a surprising property of equilateral triangles, stimulate their curiosity to wonder why the property is true, then lead them to understand how the property can be proven in an u...More: lessons, discussions, ratings, reviews,...

The applet shows a triangle which the user can resize by dragging any of its vertices.
It shows the three perpendicular bisectors of the sides and the point where they intersect - the circumc...More: lessons, discussions, ratings, reviews,...

This is a Java graphing applet that can be used online or downloaded. The purpose it to construct dynamic graphs with parameters controlled by user defined sliders that can be saved as web pages or em...More: lessons, discussions, ratings, reviews,...

This material is based upon work supported by the
National Science Foundation under Grant DUE-0226284.
Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s)
and do not necessarily reflect the views of the
National Science Foundation.